1. Field of the Invention
The present invention relates to a self-adhesive film particularly suitable for use with grafting, such as shield budding, whip and tongue graft, etc., and more specifically to a self-adhesive film which can make grafting operation easy, provides an excellent operating efficiency and maintains a high success rate of sprouting.
2. Description of the Prior Art
Recently, in the field of the fruit gardening, there is increasing severity in the economical environments. Accordingly the conversion of a harvest into fruits of high quality is now extensively being undertaken in order to conquer the competition between the fruits farmers in response to needs of higher class and variety demanded by consumers.
In general, in the grafting operation in the nursery, a method is employed in which scion buds for fruits of new plant breeding and high quality are grafted to a root stock well durable against the damage by blight and insects or change in climate. Further, a method of high worked trees (many numbers of grafting to the branches of one tree) is established as the technique for effectively switching the existing race of fruits now being produced into a new target plant breeding in order to shorten a non-harvest period for an early harvest, by which the plant breeding positively renewed.
For these grafting portions, methods which have been employed include a method for winding a self-adhesive film made of vinyl chloride tape and finally tying it; a method for using rubber strips to firmly secure the object, etc.
In this case, for protecting grafting from being dried, methods have been employed in which the whole portion thereof is covered with a plastic bag or the like, and alternatively wax cloth is used. However, in the case of vinyl chloride tapes and plastic bags, when scions are sprouting, the operation for cutting the bag open (hereafter this operation says bud-opening operation) is necessary. Since the vinyl chloride tape wound around the scions for the purpose of securing them impedes the growth of the trunk portion, the operation for removing the vinyl tape later is necessary.
Furthermore, in the case of the waxed cloth, the melted wax at a constant temperature must be prepared always. For the high worked trees conducted outdoors, this is not a suitable method in terms of difficulty of temperature management and poor operating efficiency. Also, the success rate of sprouting sometimes tends to be lowered remarkably due to being affected the operating technique, the climate conditions, etc.
For improving the above methods, a grafting method has been proposed as disclosed in Japanese Patent Publication No. 2(1990)-29290, enabling the simplification of operation in connection with the grafting operation and the remarkable enhancement of the success rate of sprouting or grafting.
That is, a film for grafting having a self-adhesive character is stretched 2 to 10 times, In case of the whip and tongue graft method, the whole scion is covered in order to secure a joined portion of grafting, and in case of the shield budding method, it is covered to seal a bud portion. Since a stretched film has a self-adhesive character in the stretched state, the final portion is placed in close contact so that tying or the like need not be done again. This simplifies the operation and completely protects the grafting portion, thus enables the remarkable enhancement of the success rate of sprouting.
Further, since the film for grafting has a deteriorating character and a moderate thickness such that the film can be bursted by the bud itself firmly germinated after the root stock and the scion have been united, the bud-opening operation is not all necessary, resulting in a substantial labor saving. Since the environment of maintaining moderate temperature and wettability are created for a given period of time by covering the entirety, this film for grafting provides various merits that it leads to early sprouting, accelerates the growth of buds, and contributes to the production of excellent plants and the growth of twigs of the scion after high worked trees.
However, there has been a problem in that since the film for grafting has the self-adhesive character, when films are placed one over another or in the form of a roll, not only they are placed in close contact with each other resulting in a difficulty of being peeled off, but also they become firmly placed in close contact due to the change with the passage of time, the change in high temperature, etc. during storage, resulting in a state of being unrolled as a single film and constituting an obstacle to a practical use.
As a method for overcoming these disadvantages as a film for grafting, there is a considered method in which the surface of the film is formed with rugged surface to mutually lower a contact area and lower a contact force. However, in the film which originally has a self-adhesive character, its contact force increases with the passage of time, which therefore is not a solution in the point of being unrolled due to the storage or the like.
Taking such problems as noted above into consideration, an easily peelable product has been proposed in which a release paper or a release film coated with a silicon resin is sandwiched and wound between films for grafting having a self-adhesive character so as to have a tape-like configuration. According to the above films, since the films having a self-adhesive character are not placed in contact with each other, they can be positively separated from each other, making it possible to help in improving the success rate of grafting as proposed in the aforementioned patent.
However, there is also a disadvantage where the release paper is used. That is, it is necessary that the films for grafting in the state of being adhered to the release paper is unrolled and cut into a desired length, and after this, the release paper and the film for grafting are separated from each other, This way of separation is unexpectedly cumbersome. The separation is difficult, because of which the films tend to be damaged, and as a result, this constitutes an obstacle to the rapid and efficient grafting operation. Furthermore, the release paper after separation is entirely waste and is often disposed at that site, giving rise to the contamination of soil and environment, The consideration and collection for not disposing them further lower the operating efficiency.